Conductive contacts are employed in performing electric characteristic inspection of a circuit configuration including a plurality of connection terminals. Specifically, these conductive contacts are made to come in physical contact with the connection terminals of the inspection apparatus to establish electric connection with the connection terminals. Wire probe conductive contacts having a circular cross-section are known as such conductive contacts. When a plurality of conductive contacts of the wire probe type are attached to a conductive contact unit, various contrivances are made to align directions in which the conductive contacts bend when an external force acts on main bodies of the conductive contacts (see, for example, Patent Documents 1 to 3). In these conventional technologies, the bending directions of the conductive contacts are aligned by shifting both ends of each of the conductive elements in a lateral direction by a predetermined distance.
FIG. 24 is a diagram of another example of attachment of the conventional conductive contact to the conductive contact unit. FIG. 25 is an enlarged diagram of the structure near the conductive contact that is in contact with an inspection apparatus. In a conductive contact 501 shown in these figures, an insulating layer 512 is formed in a main body section 511 of the conductive contact 501 excluding the ends in a longitudinal direction thereof. The main body section 511 has a circular cross-section.
A conductive contact unit that stores and holds the conductive contact 501 having the structure described above includes a two-layer first plate 600 on a side (an upper side in FIG. 24) toward which a circuit configuration for inspecting an inspection object is connected, and includes a three-layer second plate 700 on a side (a lower side in FIG. 24) toward which the inspection apparatus is connected. The two-layer first plate 600 includes an upper layer plate 601 and a lower layer plate 602, while the three-layer second plate 700 includes an upper layer plate 701, an intermediate layer plate 702, and a lower layer plate 703. An electrode 802 of a circuit board 801 of the inspection apparatus is in contact with a bottom surface of the lower layer plate 703, and one end of the attached conductive contact 501 is in contact with the electrode 802.
The upper layer plate 601 of the first plate 600 has a hole of a diameter larger than the diameter of the main body section 511 and smaller than the diameter of a section covered with an insulating layer 512. The lower layer plate 602 of the first plate 600 has a hole into which the section covered with the insulating layer 512 can enter. These two holes are stacked to be vertically coaxial.
In the second plate 700, a hole 711 of the upper layer plate 701 and a hole 712 of the intermediate layer plate 702 have the same diameter (R2). Both the main body section 511 (diameter r1) and the section covered with the insulating layer 512 (diameter r2) can enter into the holes 711 and 712. On the other hand, a hole 713 of the lower layer plate 703 has a diameter (R1) smaller than that of the hole of the upper layer plate 701. In other words, only the ends of the main body section 511 can be inserted through the hole 713. That is, the four diameters r1, r2, R1, and R2 are in a relation r1<R1<r2<R2.
The three plates of the second plate 700 are arranged such that the center axes of their holes are shifted by very small distances from one another. Consequently, these plates exert force on the attached conductive contact 501 to bend the attached conductive contact 501 in a predetermined direction.
Patent Document 1: Japanese Patent Application Laid-open No. 2001-337109
Patent Document 2: Japanese Patent Application Laid-open No. H11-248747
Patent Document 3: Japanese Patent Application Laid-open No. 2001-50982